1. Field of the Invention
The present invention relates to a clutch device used in combination with a differential device applied to conveyance means such as automobiles.
2. Description of the Related Art
As is known, an automobile is equipped with one or more differentials, each of which distributes a driving force of an engine to a pair of output axles with allowing differential motion between the axles. Some differentials have proper means for limiting or locking differential motion under proper control, thereby preventing wheels from losing traction with the road even when one of the wheels loses contact with the road. Others have means for controllably transmitting driving force to differential gear sets while the differential gear sets freely run in a steady state. So-called “part-time 4WD” automobiles utilize differentials of the latter type.
A clutch is in general used to embody these means and a plunger and a solenoid is frequently used in combination. While the clutch and the plunger rotate in accordance with rotation of the differential, the solenoid must be held stationary because the solenoid must have electric connection with electric components on the automobile and further bear reaction force in response to actuation of the plunger and the clutch. Even though the plunger and the clutch rotate but the solenoid is stationary, if strict positioning control among these devices is lost, critical energy loss or, in a serious case, malfunction will occur. Thus installation of a clutch, a solenoid and a plunger into a differential and how to put them in place are technical issues.
In general, many supplementary components are necessary to retain a solenoid and a plunger in place while allowing rotation of the differential. Japanese Patent Applications Laid-open No. 2007-92990 and No. 2007-315583 disclose related arts.